import torch
from d2l import torch as d2l
x = torch.arange(-8.0, 8.0, 0.1, requires_grad=True)
y = torch.relu(x)
d2l.plot(x.detach(), y.detach(), 'x', 'relu(x)', figsize=(5, 2.5))
# detach:对张量的作用是返回一个Tensor,其无梯度，空间和原来是一致的
d2l.plt.show()
#绘制其导数
y.backward(torch.ones_like(x), retain_graph=True)
d2l.plot(x.detach(), x.grad, 'x', 'grad of relu', figsize=(5, 2.5))
d2l.plt.show()